JP6313659B2 - Power converter - Google Patents

Description

  Embodiments described herein relate generally to a power converter that supplies power to a load simultaneously with bidirectional power conversion between a DC power supply and an AC power supply.

  The following two methods are generally known as methods for converting an AC voltage into a DC voltage. The first method uses a diode bridge circuit and a smoothing capacitor. The diode bridge circuit performs full-wave rectification on the alternating current from the alternating current power supply. The smoothing capacitor smoothes the direct current after full-wave rectification.

  In the first method, a current always flows through a series circuit of two diodes regardless of whether the AC voltage is positive or negative. At this time, in each of the two diodes, a power loss corresponding to the product of the current flowing through the diode and the forward voltage of the diode occurs.

  In the second method, a power factor correction converter (PFC) is interposed between the diode bridge circuit of the first method and the smoothing capacitor. The power factor correction converter controls the current flowing through the AC power supply to have a sine wave shape and controls the current phase to be equal to the voltage phase of the AC power supply.

  This second method also causes power loss because current flows through a series circuit of two diodes during full-wave rectification. In addition, since a current flows alternately through the field effect transistor (FET) and the diode constituting the power factor correction converter, further loss occurs.

  Further, the power factor improving converter needs to set the output voltage higher than the input voltage because the waveform of the input current needs to be a sine wave. However, the voltage required at the load is not necessarily higher than the input voltage. In that case, a step-down converter is connected after the power factor correction converter. Then, the voltage boosted by the power factor correction converter is lowered to a desired voltage. Loss also occurs during this step-down. The power conversion apparatus as a whole has a three-stage configuration of AC-DC conversion, DC-DC (step-up) conversion, and DC-DC (step-down) conversion, and the power conversion efficiency appears as a product of these conversion efficiencies. For example, when the efficiency per stage is 0.95, 0.95 × 0.95 × 0.95 = 0.86 for three stages. In other words, even an excellent conversion with an efficiency of 95% falls to 86% with a three-stage connection. Thus, even if the individual conversion efficiency is good, the conversion efficiency is remarkably lowered by using multiple stages.

  Recently, there is an increasing demand for power saving of electronic devices, and at the same time, it is an essential condition not to generate current harmonic noise so as not to adversely affect the external environment. For this reason, both the conversion efficiency improvement of the power converter device which supplies electric power to load, and a current harmonic suppression function are calculated | required.

  On the other hand, as a method of converting a DC voltage into an AC voltage, there is a method using a pulse width modulation (PWM) inverter circuit. In this method, a current corresponding to the pulse width can be supplied to the AC power supply side. For this reason, the same alternating current waveform as the voltage waveform on the AC power supply side can be generated by controlling the pulse width in synchronization with the AC voltage on the AC power supply side. However, in this method, a loss occurs in the switch elements constituting the inverter in the process of generating the pulse width, and the power conversion efficiency is lowered. This method has only an inverter function for converting a DC voltage into an AC voltage. For this reason, in order to have the function of converting the alternating voltage from the reverse direction to the direct voltage, another circuit for converting the alternating voltage to the direct voltage must be prepared.

  Thus, in order to realize bidirectional power conversion between an AC power supply and a DC power supply, it is necessary to separately provide a circuit for converting AC voltage to DC voltage and a circuit for converting DC voltage to AC voltage. is there. In addition, it is necessary to control one of the two circuits to move and the other to stop. For this reason, a circuit becomes redundant and the cost of a power converter device becomes high. In addition, the power conversion efficiency of the power conversion device is poor, and the device tends to increase in size and weight.

JP 2011-147277 A

  The problem to be solved by the present invention is to achieve both the conversion efficiency improvement and the current harmonic suppression function of a power converter that supplies power to a load simultaneously with bidirectional power conversion between an AC power source and a DC power source. It is in.

In one embodiment, the power conversion device includes a power conversion circuit and control means. The power conversion circuit connects the first switch and the second switch in series, and connects the third switch and the fourth switch in series, and the first switch, the third switch, The second switch and the fourth switch are connected to form a closed loop. Furthermore, the power conversion circuit forms a closed loop formed by connecting an AC power source, a first inductor, and a first capacitor in series. The power conversion circuit includes the first capacitor, the second capacitor between the connection point of the first switch and the second switch and the connection point of the third switch and the fourth switch. A series circuit consisting of an inductor and a primary winding of a transformer is connected. Further, the power conversion circuit connects a DC power source to both ends of the third switch and the fourth switch, and connects a load or a load circuit to the secondary winding of the transformer.
On the other hand, the control means detects the power supply voltage obtained from the means for detecting the voltage of the AC power supply, the circuit current obtained from the means for detecting the circuit current flowing through the power conversion circuit, and the means for detecting the current of the DC power supply. A set of the first switch and the fourth switch so that a current in which a high frequency component is mixed with a low frequency component of the AC power source flows through the power conversion circuit based on the direct current obtained from A pulse signal for alternately opening and closing a pair of the second switch and the third switch, a pair of the first switch and the fourth switch, a second switch, and the third switch Supplied with

The circuit block diagram of the power converter device in one Embodiment. The wave form diagram of various signals when a power converter device operate | moves as an alternating current input mode. The wave form diagram of various signals when a power converter device operate | moves as an alternating current input / direct current input mode. The wave form diagram of various signals when a power converter device operate | moves as DC input mode. The wave form diagram of various signals when a power converter device operate | moves as an alternating current input / direct current | flow output mode. The wave form diagram of various signals when a power converter device operate | moves as a direct current input / alternating current output mode. The block diagram which shows the structure of the control part in a power converter device. The signal waveform diagram used for description of a control part. The wave form diagram which shows the relationship between a control signal and each detection signal. The block diagram which shows other embodiment of a control part.

Hereinafter, an embodiment of a power converter will be described with reference to the drawings.
FIG. 1 is a circuit configuration diagram of the power conversion apparatus 100. The power conversion apparatus 100 connects an AC power supply Vac and a DC power supply Vdc as inputs or outputs for bidirectional power conversion. Further, the power conversion device 100 converts a part of the power of the AC power supply Vac or the DC power supply Vdc into an insulated DC voltage and outputs it to the load 5.

  The power conversion apparatus 100 includes first to fourth semiconductor switches (hereinafter simply referred to as switches) S1, S2, S3, S4, first and second inductors L1 and L2, and first and second capacitors. C1, C2, a transformer T1, and first and second diodes D1, D2. Each of the switches S1 to S4 uses an N-type field effect FET, or a GaN or SiC element having equivalent characteristics.

  The power conversion device 100 connects the first to fourth switches S1, S2, S3, and S4 by a method called a bridge. That is, the drain terminal of the first switch S1 is connected to the drain terminal of the third switch S3. The source terminal of the first switch S1 is connected to the drain terminal of the second switch S2. The source terminal of the third switch S3 is connected to the drain terminal of the fourth switch S4. The source terminal of the second switch S2 is connected to the source terminal of the fourth switch S4. Here, for convenience of explanation, a node name of a connection point between the source terminal of the first switch S1 and the drain terminal of the second switch S2 is referred to as an M1 terminal. A node name of a connection point between the source terminal of the third switch S3 and the drain terminal of the fourth switch S4 is referred to as an M2 terminal.

  The power conversion device 100 connects the first capacitor C1, the second inductor L2, and the primary winding Lp of the transformer T1 in series between the MI terminal and the M2 terminal. In the power conversion apparatus 100, an AC power supply Vac is connected to both ends of the first capacitor C1 via a first inductor L1. The power conversion apparatus 100 connects the DC power supply Vdc between the source terminal of the third switch S3 and the drain terminal of the fourth switch S4.

  The power conversion device 100 connects two secondary windings Ls1 and Ls2 of the transformer T1 in series. In the power conversion apparatus 100, the anode terminal of the first diode D1 is connected to one end (secondary winding Ls1 side) of the secondary windings Ls1 and Ls2 connected in series, and the other end (secondary winding Ls2 side). ) To the anode terminal of the second diode D2. The power conversion device 100 connects the cathode terminal of the first diode D1 to the cathode terminal of the second diode D2. In the power conversion device 100, between the middle point where the secondary winding Ls1 and the secondary winding Ls2 are connected in series and the connection point between the cathode terminals of the first and second diodes D1 and D2, The second capacitor C3 and the load 5 are connected in parallel.

  The first and second diodes D1, D2 and the second capacitor C3 constitute a rectifying / smoothing circuit. For example, when a current flows through the second inductor L2 from the connection point between the first inductor L1 and the first capacitor C1 to the primary winding Lp side of the transformer T1, the first diode D1 Assume that the winding of the transformer T1 is set so that a current flows. Then, when the current flowing through the second inductor L2 is reversed, the current flows to the second diode D2 side. As a result, regardless of the direction of the circuit current Is1, a current is supplied to the second capacitor C2 from the first diode D1 side or the second diode D2 side. That is, regardless of whether the circuit current Is1 is positive or negative, a part of the circuit current Is1 flows into the second capacitor C2 via the transformer T1, and is stored as electric charge in the second capacitor C2.

  In the present embodiment, the configuration up to the rectifying and smoothing circuit composed of the first and second diodes D1 and D2 and the second capacitor C2 and the load 5 connected to the smoothed voltage output is referred to as a load circuit 10. . Note that the load circuit 10 defined here is not limited to the above embodiment. The load circuit 10 is arranged between the above-described secondary windings Ls1, Ls2 and the load 5, and is a general term for a circuit configuration that electrically connects both.

  The power conversion device 100 includes voltage detection units 1 and 4 and current detection units 2 and 3. Specifically, the power conversion device 100 connects the voltage detection unit 1 between both terminals of the AC power supply Vac. The voltage detection unit 1 detects a voltage applied to the power conversion device 100 from the AC power supply Vac, that is, a so-called AC power supply voltage, and outputs a detection signal (voltage signal) Vs1.

  The power conversion device 100 connects the current detection unit 2 between the negative terminal of the DC power supply Vdc and the source terminal of the second switch S2. The current detection unit 2 detects a current flowing through the DC power supply Vdc, that is, a so-called DC power supply current, and outputs a detection signal (current signal) Is2. The position of the current detection unit 2 is not limited to the above embodiment. For example, even if the current detector 2 is connected between the positive terminal of the DC power supply Vdc and the drain terminal of the first switch S2, the current flowing through the DC power supply Vdc can be detected.

  The power conversion device 100 connects the current detection unit 3 between the second inductor L2 and the primary winding Lp of the transformer T1. The current detection unit 3 detects a current flowing through the second inductor L2, that is, a so-called circuit current, and outputs a detection signal (current signal) Is1.

  The power conversion device 100 connects the voltage detection unit 4 between both terminals of the second capacitor C2. The voltage detection unit 4 detects a voltage applied to the load 5 from the second capacitor C2, that is, an output voltage, and outputs a detection signal (voltage signal) Vs2.

  The power conversion device 100 includes a control unit 6. The control unit 6 receives the detection signals Vs1, Vs2, Is1, Is2 and the control signal CTL output from the voltage detection units 1 and 4 and the current detection units 2 and 3, respectively. The control signal CTL is a signal whose level is dynamically adjusted by switching a control switch (not shown).

  Based on these input signals Vs1, Vs2, Is1, Is2, and CTL, the control unit 6 generates gate drive signals P1, P2, P3, and P4 of the first to fourth switches S1 to S4 that form a bridge. The gate drive signals P1, P2, P3, and P4 are output to the gate terminals of the switches S1 to S4, respectively. Each of the switches S1, S2, S3, S4 conducts while the gate drive signals P1, P2, P3, P4 are supplied to the gate terminals, respectively.

  The power conversion device 100 forms a low-pass filter by the first inductor L1 and the first capacitor C1. For this reason, the current flowing to the AC power supply Vac side via the first inductor L1, that is, the so-called AC power supply current is only a low frequency component of 50 Hz, for example. On the other hand, the power conversion apparatus 100 can obtain a high-frequency current of 100 [kHz: kilohertz], for example, by switching the first to fourth switches S1, S2, S3, and S4.

  In order to obtain this high-frequency current, the power conversion apparatus 100 uses a pair of positive and negative envelopes that define the peak of the circuit current Is1. The envelope is sinusoidal. The power conversion device 100 includes a pair of the first switch S1 and the fourth switch S4, and a pair of the second switch S2 and the third switch S3 so that the direction of the current is switched between the pair of envelopes. Are alternately switched at an appropriate timing. By this switching, for example, a high-frequency current of 100 [kHz] is generated.

  When a high-frequency current of 100 [kHz] is generated, a current flowing through the first capacitor C1 to the first switch S1 or the second switch S2 is a low-frequency component current of 50 [Hz: Hertz]. And 100 [kHz] high-frequency component current. Therefore, the circuit current (detection signal Is1) detected by the current detection unit 3 is a current in which a low frequency component of 50 [Hz] and a high frequency component of 100 [kHz] are mixed. As a result, the power conversion apparatus 100 as a whole operates with a mixture of alternating currents having these two types of frequencies.

  Next, the operation mode of the power conversion device 100 will be described. Here, a commercial power source of 100 [V: volts] and 50 [Hz] is used as the AC power source Vac, and a DC power source of 400 [V] is used as the DC power source Vdc, and 200 [W: Assume that the power of [Watt] is supplied.

  First, an operation mode (hereinafter referred to as an AC input mode) for transmitting all the power of the AC power supply Vac to the load 5 will be described. Incidentally, since the AC voltage is 100 [V], a current of 2 [A: ampere] is required to obtain power of 200 [W]. That is, if the current finally flowing into the AC power supply Vac via the first inductor L1 is 2 [A], 200 [W] of power can be supplied to the load 5.

  In the AC input mode, no current flows through the DC power supply Vdc in either direction. That is, there is no power supply from the DC power supply Vdc, and there is no power output from the DC power supply Vdc. FIG. 2 shows waveforms of the signals Vs1, Is1, Iac, env1, env2, and Is2 in the AC input mode. The signal Iac is an AC power supply current detection signal. The signals env1 and env2 are a pair of positive and negative envelope signals that define the circuit current.

  As shown in FIG. 2, in the AC input mode, the power conversion apparatus 100 generates a pair of positive and negative envelope signals env1 and env2 so that the amplitude and phase are similar to the detection signal Vs1 of the AC power supply voltage. Then, a circuit current (detection signal Is1) is caused to flow between the envelope signals env1 and env2. Then, the average value of the circuit current becomes equal to the AC power supply current represented by the detection signal Iac.

  Thus, when the envelope signals env1 and env2 are set so that the phase and amplitude are the same as those of the AC power supply Vac, the AC power supply current is in phase with the AC power supply Vac. This event means that power is supplied to the load circuit 10 from the AC power supply Vac. That is, AC power supply Vac acts as a power supply source to load 5.

  On the other hand, the current flowing through the DC power supply Vdc is increased or decreased within one cycle of the AC power supply Vac as shown by the detection signal Is2, but on average, the current is zero. This zero current state means that no current is generated from the DC power supply Vdc. That is, the DC power supply Vdc does not act as a power supply source to the load 5. Further, the DC power supply Vdc does not act as a power supply destination for bidirectional power conversion.

  Next, an operation mode for transmitting the power of the AC power supply Vac and the power of the DC power supply Vdc to the load 5 (hereinafter referred to as AC input / DC input mode) will be described.

  FIG. 3 shows waveforms of the signals Vs1, Is1, Iac, env1, env2, and Is2 in the AC input / DC input mode. As shown in FIG. 3, in the AC input / DC input mode, the power conversion apparatus 100 makes the amplitudes of the envelope signals env1 and env2 smaller than in the AC input mode. The phases of the envelope signals env1 and env2 are the same as those of the AC power supply Vac. For example, when the amplitudes of the envelope signals env1 and env2 are half that in the AC input mode, the AC power supply current represented by the detection signal Iac is also half that in the AC input mode. This event means that the power supplied from the AC power supply Vac to the load circuit 10 is halved.

  On the other hand, the width between the positive envelope signal env1 and the negative envelope signal env2 is the same as in the AC input mode. For this reason, the electric power supplied to the load 5 is the same as in the AC input mode. Therefore, power supply from the AC power supply Vac is insufficient. The power conversion apparatus 100 supplements this shortage by supplying power from the DC power supply Vdc.

  In the AC input / DC input mode, the waveform of the DC power supply current represented by the detection signal Is2 is entirely shifted to the minus side (lower than the zero level in FIG. 3). As a result, the area of the section where the DC power supply current takes a negative value is larger than the area of the section where the DC power supply current takes a positive (+: plus) value. This event means that the load circuit 10 is supplied with power from the DC power supply Vdc because the DC power supply current has a negative value when averaged. That is, both the AC power supply Vac and the DC power supply Vdc act as a power supply source to the load 5.

  Next, an operation mode (hereinafter referred to as a DC input mode) for transmitting all the power of the DC power supply Vdc to the load 5 will be described.

  FIG. 4 shows waveforms of the signals Vs1, Is1, Iac, env1, env2, and Is2 in the DC input mode. As shown in FIG. 4, in the DC input mode, the power conversion apparatus 100 sets the amplitudes of the envelope signals env1 and env2 to zero. When the amplitude becomes zero, the envelope signals env1 and env2 are linear. Therefore, even if a circuit current (detection signal Is1) is passed between the envelope signals env1 and env2, the AC power supply current represented by the detection signal Iac becomes zero. This zero current state means that no current is generated from the AC power supply Vac. That is, AC power supply Vac does not act as a power supply source to load 5. The AC power supply Vac does not act as a power supply destination for bidirectional power conversion.

  On the other hand, the width between the positive envelope signal env1 and the negative envelope signal env2 is the same as in the AC input mode. For this reason, the electric power supplied to the load 5 is the same as in the AC input mode. Therefore, the power conversion device 100 supplements the power supply from the AC power supply Vac with the power supply from the DC power supply Vdc.

  In the DC input mode, the waveform of the DC power supply current represented by the detection signal Is2 is all shifted to the minus side (lower than the zero level in FIG. 4). This event means that the load circuit 10 is supplied with power from the DC power supply Vdc. That is, DC power supply Vdc acts as a power supply source to load 5.

  Next, an operation mode (hereinafter referred to as AC input / DC output mode) for transmitting the power of the AC power supply Vac to the load 5 and also to the DC power supply Vsc will be described.

  FIG. 5 shows waveforms of the signals Vs1, Is1, Iac, env1, env2, and Is2 in the AC input / DC output mode. As shown in FIG. 5, in the AC input / DC output mode, the power conversion apparatus 100 reduces the width between the positive envelope signal env1 and the negative envelope signal env2. The phase and amplitude of the envelope signals env1 and env2 are the same as in the AC input mode. In this case, the AC power supply current represented by the detection signal Iac is in phase with the AC power supply Vac. This event means that power is supplied to the load circuit 10 from the AC power supply Vac. That is, AC power supply Vac acts as a power supply source to load 5.

  On the other hand, the waveform of the DC power supply current represented by the detection signal Is2 is shifted to the positive side as a whole (above the zero level in FIG. 5). As a result, the area of the section where the DC power supply current takes a positive value is smaller than the area of the section where the DC power supply current takes a negative value. This event means that the DC power supply current has a positive value when averaged, and thus the DC power supply Vdc is supplied with power from the AC power supply Vac. That is, AC power supply Vac not only functions as a power supply source to load 5, but also functions as a power supply source to DC power supply Vdc.

  Next, an operation mode (hereinafter referred to as DC input / AC output mode) for transmitting the power of the DC power supply Vdc to the load 5 and also to the AC power supply Vac will be described.

  FIG. 6 shows waveforms of the signals Vs1, Is1, Iac, env1, env2, and Is2 in the DC input / AC output mode. As shown in FIG. 6, in the DC input / AC output mode, the power converter 100 reverses the phases of the envelope signals env1 and env2 to those in the AC input mode, and at the same time, the positive envelope signal env1 and the negative envelope signal env2 Reduce the width between the two. The amplitudes of the envelope signals env1 and env2 are the same as in the AC input mode. In this case, the AC power supply current represented by the detection signal Iac has a phase opposite to that of the AC power supply Vac. This event means that power is supplied to the AC power supply Vac.

  In the DC input / AC output mode, the waveform of the DC power supply current represented by the detection signal Is2 is all shifted to the minus side (lower than the zero level in FIG. 6). This event means that the load circuit 10 is supplied with power from the DC power supply Vdc. That is, DC power supply Vdc not only functions as a power supply source to load 5, but also functions as a power supply source to AC power supply Vac.

  Each operation mode described above is controlled by the control unit 6. Then, next, the control part 6 is demonstrated using FIGS. 7-9.

  FIG. 7 is a block diagram illustrating a configuration of the control unit 6. As shown in FIG. 7, the control unit 6 includes a zero cross detection unit 601, a sine wave generation unit 602, an envelope generation unit 603, an output current adjustment unit 604, a DC current adjustment unit 605, a positive circuit current determination unit 606, and a negative side. Circuit current determination unit 607, latch circuit 608, first delay generation unit 609, and second delay generation unit 610.

  The zero cross detection unit 601 receives the detection signal Vs1. The detection signal Vs1 is an AC power supply voltage detected by the voltage detection unit 1. The zero cross detection unit 601 detects the phase period of the AC power supply voltage from the detection signal Vs1.

  The sine wave generation unit 602 receives as input a signal indicating the phase and period detected by the zero cross detection unit 601. The sine wave generation unit 602 generates a sine wave synchronized with the phase and cycle of the AC power supply voltage from the signal of the zero cross detection unit 601.

  The envelope generation unit 603 receives a signal indicating the sine wave generated by the sine wave generation unit 602 as an input. The envelope generation unit 603 receives the coefficient k1 given from the output current adjustment unit 604 and the coefficient k2 given from the DC current adjustment unit 605 as inputs. The envelope generation unit 603 uses the sine wave waveform generated by the sine wave generation unit 602 as a basic waveform of the envelope, and adjusts this basic waveform with the coefficients k1 and k2 to generate a pair of positive and negative envelope signals env1 and env2. To do.

  The output current adjustment unit 604 receives the detection signal Vs2. The detection signal Vs2 is an output voltage detected by the voltage detection unit 4. The output current adjustment unit 604 outputs the coefficient k1 according to the change in the output voltage. The coefficient k1 relates to the adjustment of the width sandwiched between the positive envelope signal env1 and the negative envelope signal env2. For example, when the output voltage is high, the output current adjustment unit 604 outputs a coefficient k1 that narrows the width of the envelope signals env1 and env2. Conversely, when the output voltage is low, the output current adjustment unit 604 outputs a coefficient k1 that increases the width of the envelope signals env1 and env2. In the present embodiment, it is assumed that when the coefficient k1 is increased, the widths of the envelope signals env1 and env2 are increased, and when the coefficient k1 is decreased, the widths of the envelope signals env1 and env2 are decreased.

  The direct current adjustment unit 605 receives the detection signal Is2 and the control signal CTL as inputs. The detection signal Is2 is a DC power supply current detected by the current detection unit 2. The direct current adjustment unit 605 outputs a coefficient k2 according to the direct current power supply current Is2 and the level of the control signal CTL. The coefficient k2 relates to the amplitude adjustment in the envelope signals env1 and env2. For example, when the DC power supply current is larger than the control signal CTL, the DC current adjustment unit 605 outputs a coefficient k2 that increases the amplitudes of the envelope signals env1 and env2. As the amplitudes of the envelope signals env1 and env2 increase, the DC power supply current decreases. Conversely, when the DC power supply current is smaller than the control signal CTL, the DC current adjustment unit 605 outputs a coefficient k2 that decreases the amplitude of the envelope signals env1 and env2. When the amplitudes of the envelope signals env1 and env2 are reduced, the DC power supply current is increased. In the present embodiment, it is assumed that when the coefficient k2 is reduced, the amplitudes of the envelope signals env1 and env2 are increased, and when the coefficient k2 is increased, the amplitudes of the envelope signals env1 and env2 are decreased. Such magnitude of the amplitude can be realized by increasing or decreasing the amplification factor for the sine wave signal.

  The circuit current determination unit 606 receives the positive envelope signal env1 and the detection signal Is1 as inputs. The detection signal Is1 is a circuit current detected by the current detection unit 3. The circuit current determination unit 606 outputs nothing when the circuit current is smaller than the envelope signal env1. When the circuit current reaches or exceeds the envelope signal env1, the circuit current determination unit 606 outputs a pulse signal SET.

  The circuit current determination unit 607 receives the negative envelope signal env1 and the detection signal Is1 as inputs. The detection signal Is1 is a circuit current detected by the current detection unit 3. The circuit current determination unit 607 outputs nothing when the circuit current is larger than the envelope signal env2. When the circuit current reaches or falls below the envelope signal env2, the circuit current determination unit 607 outputs a pulse signal RESET.

  The latch circuit 608 inputs the pulse signal SET from the circuit current determination unit 606 to the set terminal, and inputs the pulse signal RESET from the circuit current determination unit 607 to the reset terminal. When the pulse signal SET is input to the set terminal, the latch circuit 608 sets the normal output Q to the “H” state and simultaneously sets the inverted output Qber to the “L” state to maintain these states. When the pulse signal RESET is input to the reset terminal, the latch circuit 608 sets the normal output Q to the “L” state and simultaneously sets the inverted output Qber to the “H” state to maintain these states.

  The first delay generation unit 609 receives the normal output Q of the latch circuit 608 as an input. The first delay generation unit 609 generates a predetermined delay time d1 when the state of the normal rotation output Q is switched from the “L” state to the “H” state, and the normal rotation output Q delayed by this delay time d1. The signal Qd is output. The signal Qd is output from the control unit 6 as gate drive signals P1 and P4 for the first switch S1 and the fourth switch S4.

  The second delay generation unit 610 receives the inverted output Qber of the latch circuit 608 as an input. The second delay generation unit 610 generates a predetermined delay time d2 when the state of the inverted output Qber switches from the “L” state to the “H” state, and the signal of the inverted output Qbar delayed by this delay time d2 Qbard is output. The signal Qbard is output from the control unit 6 as gate drive signals P2 and P3 for the second switch S2 and the third switch S3.

  FIG. 8 shows the waveforms of the detection signals Is1, Iac input to the control unit 6, the waveforms of various signals env1, env2, SET, RESET, P1 to P4 generated by the control unit 6, and the M1 terminal and the M2 terminal. It is a wave form diagram which shows the waveform of the voltage signal applied.

  In FIG. 8, time points t0, t2, and t4 are time points (negative arrival point q2) when the circuit current represented by the detection signal Is1 reaches the negative envelope signal env2. On the other hand, time points t1, t3, and t5 are time points (positive side arrival point q1) when the circuit current represented by the detection signal Is1 reaches the positive envelope signal env1.

  When the circuit current reaches the positive envelope signal env1, a pulse signal SET is output by the action of the circuit current determination unit 606. Then, the gate drive signals P1 and P4 become “L” in synchronization with the pulse signal SET by the action of the latch circuit 608 and the first and second delay generation units 609 and 610. Further, after the delay time d2 has elapsed, the gate drive signals P2 and P3 become “H”.

  When the gate drive signals P1 and P4 become “L”, the first switch S1 and the fourth switch S4 are opened. When the gate drive signals P2 and P3 become “H”, the second switch S2 and the third switch S3 are energized. When the first switch S1 and the fourth switch S4 are opened, the voltage at the M1 terminal becomes zero level, and the voltage at the M2 terminal becomes the voltage of the DC power supply Vdc.

  When the circuit current reaches the negative envelope signal env2, the pulse signal RESET is output by the action of the circuit current determination unit 607. Then, the gate drive signals P2 and P3 become “L” in synchronization with the pulse signal RESET by the action of the latch circuit 608 and the first and second delay generation units 609 and 610. Further, after the delay time d1 has elapsed, the gate drive signals P1 and P4 become “H”.

  When the gate drive signals P2 and P3 become “L”, the second switch S2 and the third switch S3 are opened. When the gate drive signals P1 and P4 become “H”, the first switch S1 and the fourth switch S4 are energized. When the second switch S2 and the third switch S3 are opened, the voltage at the M2 terminal becomes zero level, and the voltage at the M1 terminal becomes the voltage of the DC power supply Vdc.

  As described above, the state in which the voltage is zero level and the state in which the voltage of the DC power supply Vdc is applied are alternately repeated at the M1 terminal and the M2 terminal. Here, a series circuit of a first capacitor C1, a second inductor L2, and a transformer T1 is connected between the M1 terminal and the M2 terminal. Therefore, a high-frequency alternating current synchronized with the on / off switching timings of the switches S1 to S4 flows through the series circuit.

  FIG. 9 is a waveform diagram showing the relationship between the control signal CTL and the respective detection signals Vs1, Iac, Is2, and Is1. In FIG. 9, the horizontal axis indicates time. Then, it is assumed that the level of the control signal CTL at the time point a is n (n> 0). Further, it is assumed that the level of the control signal CTL at the time point b is n / 2, the level of the control signal CTL at the time point c is 0, and the level of the control signal CTL at the time point xc is − (n / 2) and the level of the control signal CTL at the time point xa is assumed to be 3n / 2.

  First, the operation at the time point a will be described. At time point a, as is apparent from the detection signal Vs1 and the detection signal Iac, an AC power supply current having the same phase as the voltage phase of the AC power supply Vac flows. At this time, the DC power supply current indicated by the detection signal Is2 takes a positive or negative value according to the phase of the AC power supply Vac, but when averaged, the current is zero. That is, no power is supplied from the DC power supply Vdc side to the load circuit 10 side, and no power is supplied to the DC power supply Vdc. Therefore, the power supplied to the load 5 is only the power from the AC power supply Vac.

  Such an operation at the time point a coincides with the operation in the AC input mode. That is, by setting the level of the control terminal CTL to n, the control unit 6 can set the operation mode of the power converter to the AC input mode. Incidentally, in the AC input mode, since electric power is supplied from the AC power supply Vac to the load circuit 10 side, the current supplied from the AC power supply Vac is maximized.

  Next, the operation at time point b will be described. At time point b, the amplitudes of envelope signals env1 and env2 are smaller than at time point a. Along with this, the AC power supply current decreases. On the other hand, the DC power supply current shifts in the negative direction as a whole and becomes a negative value.

  The width between the positive envelope signal env1 and the negative envelope signal env2 is the same as that at time point a. Therefore, there is no change in the power supplied to the load 5. That is, at the time point b, the power supplied from the AC power supply Vac to the load circuit 10 decreases, and the decrease is supplemented by the power supply from the DC power supply Vdc.

  Such an operation at time point b coincides with the AC input / DC input mode. That is, by setting the level of the control terminal CTL to a positive value smaller than n, the control unit 6 can set the operation mode of the power converter to the AC input / DC input mode.

  Next, the operation at time point c will be described. At the time point c, the amplitudes of the envelope signals env1 and env2 become smaller than those at the time point b, and the AC power supply current becomes zero. On the other hand, the negative value of the DC power supply current is further larger than that at time point b.

  The width sandwiched between the positive envelope signal env1 and the negative envelope signal env2 is the same as at time point a and time point b. Therefore, there is no change in the power supplied to the load 5. In other words, at time point c, no power is supplied from the AC power supply Vac to the load circuit 10, and all is provided by power supply from the DC power supply Vdc.

  Such an operation at the time point c coincides with the DC input mode. That is, by setting the level of the control terminal CTL to level 0 at the time point c, the control unit 6 can set the operation mode of the power converter to the DC input mode.

  Next, the operation at the time point xc will be described. At the time point xc, the phase of the AC power supply current is opposite to that at the time points a, b, and c. This means that power is supplied to the AC power supply Vac. On the other hand, the negative value of the DC power supply current is larger than that at time point c.

  The width sandwiched between the positive envelope signal env1 and the negative envelope signal env2 is the same as the time points a, b, and c. Therefore, there is no change in the power supplied to the load 5. That is, at the time point xc, the power from the DC power supply Vdc is supplied not only to the load circuit 10 but also to the AC power supply Vac.

  Such an operation at the time point xc coincides with the DC input / AC output mode. That is, by setting the level of the control terminal CTL to a negative value, the control unit 6 can set the operation mode of the power converter to the DC input / AC output mode.

  Next, the operation at time point xa will be described. At time point xa, the amplitudes of envelope signals env1 and env2 are larger than at time point a. Along with this, the AC power supply current increases. On the other hand, the DC power supply current shifts in the positive direction as a whole and becomes a positive value. A positive DC power supply current means that power is supplied to the DC power supply Vdc.

  The width sandwiched between the positive envelope signal env1 and the negative envelope signal env2 is not different from the time points a, b, c, and xc. Therefore, there is no change in the power supplied to the load 5. That is, at the time point xa, the power from the AC power supply Vac is supplied not only to the load circuit 10 but also to the DC power supply Vdc.

  The operation at the time point xa matches the operation in the AC input / DC output mode. That is, by making the level of the control terminal CTL higher than the level n at the time point a, the control unit 6 can set the operation mode of the power converter to the AC input / DC output mode.

  In this way, the power conversion apparatus 100 adjusts the level of the control signal CTL, thereby changing the AC input mode, the AC input / DC input mode, the DC input mode, the AC input / DC output mode, and the DC input / AC output mode. Two operation modes can be selectively switched and used.

  When the AC input mode and the AC input / DC output mode are selected, the AC power source Vac can be used as a 100% power supply source to the load circuit 10 or the load 5. Similarly, when the DC input mode or the DC input / AC output mode is selected, the DC power supply Vdc can be used as a 100% power supply source to the load circuit 10 or the load 5. On the other hand, when the AC input / DC input mode is selected, the AC power source Vac and the DC power source Vdc are used as power supply sources to the load circuit 10 or the load 5, and the supply ratio can be arbitrarily set. . In addition, in any of the operation modes, there is no change in the amount of power supplied to the load 5, so that stable operation can be guaranteed.

  When the AC input / DC output mode is selected, power can be supplied not only to the load 5 but also to the DC power supply Vdc from the AC power supply Vac. Therefore, when the DC power supply Vdc is a rechargeable battery, for example, the DC power supply Vdc can be charged while driving the load 5.

  Further, when the DC input / AC output mode is selected, power can be supplied not only to the load 5 but also to the AC power supply Vac from the DC power supply Vdc. Therefore, the AC power source Vac is a commercial power source, and even if a power failure occurs in the commercial power source, power can be supplied to the system of the AC power source Vac using the power of the DC power source Vdc while continuing to supply power to the load 5. There is an advantage that the AC power source Vac can be used even in the event of a power failure.

  As described above, a very high-variation function can be realized as a mechanism for supplying power to the load 5. For example, the commercial power supply AC power supply Vac is normally used, and when a power failure occurs, the power can be effectively used, for example, by quickly switching to the battery direct current power supply Vdc. In addition, it is possible to prevent the load from being stopped due to a power failure, and is useful as a dual power supply in a wide range of industrial fields. Therefore, even if the power source is unstable, it can be complemented with the AC and DC power sources to operate, and a highly reliable power supply system can be provided.

  Moreover, the power converter device 100 operate | moves on the conditions of ZVS (zero voltage switching). Therefore, it is possible to realize efficient power conversion with very little switching loss. For this reason, the use effect is great in all industrial fields where an energy-saving effect is expected.

  In the above-described embodiment, the case where the five operation modes are switched by adjusting the level of the control signal CTL from the outside is illustrated. The control signal CTL is not limited to a signal whose level is adjusted linearly. You may apply the control signal CTL which adjusts a level in steps. In this case, the control unit 6 includes a data table in which the level of the control signal CTL and each operation mode are associated with each other in one-to-one correspondence. May be determined.

  As shown in FIG. 10, a setting unit 611 for the coefficient k2 may be provided instead of the DC current adjustment unit 605, and the fixed coefficient k2 may be output to the envelope generation unit 603. With such a configuration, the power conversion device 100 can be used as a dedicated machine in any one of the operation modes depending on the value of the coefficient k2 set by the setting unit 611.

  In addition, although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1, 4 ... Voltage detection part 2, 3 ... Current detection part, 5 ... Load, 6 ... Control part, 10 ... Load circuit, 100 ... Power converter, 601 ... Zero cross detection part, 602 ... Sine wave generation part, 603 ... Envelope generation unit 604... Output current adjustment unit 605... DC current adjustment unit 606... Positive circuit current determination unit 607... Negative circuit current determination unit 608. Generation unit, 610, second delay generation unit, Vac, AC power supply, Vdc, DC power supply.

Claims (5)

The first switch and the second switch are connected in series, and the third switch and the fourth switch are connected in series, and the first switch, the third switch, and the second switch are connected to each other. A fourth switch is connected to form a closed loop, and a closed loop formed by connecting an AC power source, a first inductor, and a first capacitor in series is formed, and the first switch and the second switch are connected to each other. A series circuit composed of the first capacitor, the second inductor, and the primary winding of the transformer is connected between the connection point of the switch and the connection point of the third switch and the fourth switch. A power conversion circuit for connecting a DC power source to both ends of the third switch and the fourth switch, and connecting a load or a load circuit to the secondary winding of the transformer;
A power supply voltage obtained from the means for detecting the voltage of the AC power supply, a circuit current obtained from the means for detecting current flowing through the power conversion circuit, and a DC current obtained from the means for detecting current flowing through the DC power supply The first switch and the fourth switch, and the second switch and the switch so that a current in which a high frequency component is mixed with a low frequency component of the AC power source flows through the power conversion circuit. Control for supplying a pulse signal for alternately opening and closing a set with the third switch to the set of the first switch and the fourth switch, and the set of the second switch and the third switch Means,
A power conversion device comprising: The control means includes
Sine wave generating means for generating a sine wave in phase with the voltage of the AC power source based on a voltage signal detected by the means for detecting the voltage of the AC power source;
Based on the sine wave generated by the sine wave generating means, a voltage signal obtained from the means for detecting the voltage applied to the load, and a current signal obtained from the means for detecting the current flowing through the DC power supply, An envelope generating means for determining a target value of the current flowing through the AC power source, and generating a positive side envelope and a negative side envelope by giving a predetermined width to the target value;
It is determined whether or not a circuit current obtained from a means for detecting a current flowing through the power conversion circuit falls within a range between the positive envelope and the negative envelope, and the circuit current is determined to be within the positive envelope. And pulse generation means for generating the pulse signal at a timing deviating from the range between the negative envelope and the negative envelope,
The power converter according to claim 1, further comprising: The control means includes
A sine wave generating means for generating a sine wave having a phase opposite to that of the AC power supply voltage based on an AC voltage signal detected by the means for detecting the voltage of the AC power supply;
Based on the sine wave generated by the sine wave generating means, a voltage signal obtained from the means for detecting the voltage applied to the load, and a current signal obtained from the means for detecting the current flowing through the DC power supply, An envelope generating means for determining a target value of the current flowing through the AC power source, and generating a positive side envelope and a negative side envelope by giving a predetermined width to the target value;
It is determined whether or not a circuit current obtained from a means for detecting a current flowing through the power conversion circuit falls within a range between the positive envelope and the negative envelope, and the circuit current is determined to be within the positive envelope. And pulse generation means for generating the pulse signal at a timing deviating from the range between the negative envelope and the negative envelope,
The power converter according to claim 1, further comprising: The control means includes
Output current adjusting means for outputting a first coefficient for adjusting the output current according to a voltage signal obtained from the means for detecting the voltage applied to the load;
Further comprising
When the first coefficient is a value for adjusting the output current to increase, the envelope generating means widens the width of the positive envelope and the negative envelope, and 4. The power conversion according to claim 2, wherein when the coefficient is a value that adjusts the output current in a decreasing direction, a width between the positive envelope and the negative envelope is narrowed. 5. apparatus. A first signal for adjusting the amplitude of the positive envelope and the negative envelope by a current signal obtained from a means for detecting a current flowing through the DC power supply and a control signal for setting a current flowing through the DC power supply. DC current adjusting means for outputting a coefficient of 2,
Further comprising
When the second coefficient is a value that adjusts the amplitude in the direction of increasing the amplitude, the envelope generating means increases the amplitude of the positive-side envelope and the negative-side envelope, and 5. The method according to claim 2, wherein when the coefficient is a value that adjusts the amplitude in a decreasing direction, the amplitude of the positive envelope and the negative envelope is decreased. Bidirectional power conversion device described in 1.

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